(a). Field of the Invention
The present invention relates to a cathode-ray tube (CRT) having a faceplate panel and, more particularly, to a CRT faceplate panel for producing a uniform and clear visual image across the entire area of a viewing screen.
(b). Description of the Related Art
Generally, CRTs are designed to reproduce a picture image on a screen of a faceplate panel by exciting phosphors coated on an interior surface of the faceplate panel with electron beams emitted from an electron gun and passing through apertures of a color-selecting shadow mask. The shadow mask ensures that each electron beam lands on the correct phosphor.
The faceplate panel is usually formed with a transparent glass plate having curved interior and exterior surfaces. These curved surfaces enable the panel to withstand the high-vacuum pressure in the CRT and facilitate the landing of the electron beams on the phosphor screen.
However, such a faceplate panel involves a relatively broad light-reflecting exterior area in peripheral portions thereby deteriorating the brightness of those areas and distorting the appearance of the picture.
To remedy this problem, a glass plate having flat interior and exterior surfaces for the CRT faceplate panel has been developed. Such a panel employs a flat tension mask to perform the color-selecting function, the flat tension mask corresponding to the flat interior surface of the panel. The flat tension mask has predetermined horizontal and vertical tensional strengths to prevent the occurrence of a doming phenomenon.
However, in this type of panel, The visual images realized through the phosphor screen and refracted on the panel appear depressed to the user in the center portion of the viewing screen. The problem becomes more severe with larger-sized screens.
To overcome this drawback, Japanese Patent Laid-Open Publication Nos. Hei 6-44926 and 6-36710 introduce a CRT faceplate panel which is flat on an exterior surface but curved on an interior surface. However, the images realized through these inventions appear bulged outward. Further, because the peripheral portions of the panel are considerably thicker than center portions, the brightness of the screen is deteriorated.